* [PATCH v3] mm: memblock: show all region flags in debugfs
@ 2026-09-02 7:59 Meijing Zhao
2026-09-03 13:36 ` Mike Rapoport
0 siblings, 1 reply; 2+ messages in thread
From: Meijing Zhao @ 2026-09-02 7:59 UTC (permalink / raw)
To: Mike Rapoport, Andrew Morton
Cc: Meijing Zhao, linux-mm, linux-kernel, Wandun Chen
From: Meijing Zhao <zhaomeijing@lixiang.com>
Commit 493f349e38d0 ("memblock: Add flags and nid info in memblock
debugfs") made memblock_debug_show() stop after finding the first set
flag. A memblock region can carry multiple flags, so the remaining flags
are hidden from debugfs.
Walk all bits in the region flags and print every set flag separated by
"|". Keep walking beyond flagname[] so that a set flag without a known
name is reported as UNKNOWN rather than silently ignored.
Fixes: 493f349e38d0 ("memblock: Add flags and nid info in memblock debugfs")
Signed-off-by: Meijing Zhao <zhaomeijing@lixiang.com>
---
Changes in v3:
- Rebase onto v7.3-rc1 and send the former patch 2/3 as a standalone
patch.
- Move flags and first into the reg->flags block.
- Remove the redundant flagname[j] NULL check.
- Keep the existing NONE output unchanged.
- Drop the debugfs synchronization change. As discussed during the v2
review, proper locking for runtime memblock accesses needs a broader
design and will be addressed separately.
v2: https://lore.kernel.org/linux-mm/20260821020910.3428585-1-zhaomeijing100@gmail.com/
mm/memblock.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/mm/memblock.c b/mm/memblock.c
index 9ce86349a29f..021db49eb7fc 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -2908,14 +2908,18 @@ static int memblock_debug_show(struct seq_file *m, void *private)
else
seq_printf(m, "%4c ", 'x');
if (reg->flags) {
- for (j = 0; j < count; j++) {
- if (reg->flags & (1U << j)) {
- seq_printf(m, "%s\n", flagname[j]);
- break;
- }
+ unsigned int flags = reg->flags;
+ bool first = true;
+
+ for (j = 0; flags; j++, flags >>= 1) {
+ if (!(flags & 1))
+ continue;
+ if (!first)
+ seq_putc(m, '|');
+ seq_puts(m, j < count ? flagname[j] : "UNKNOWN");
+ first = false;
}
- if (j == count)
- seq_printf(m, "%s\n", "UNKNOWN");
+ seq_putc(m, '\n');
} else {
seq_printf(m, "%s\n", "NONE");
}
--
2.25.1
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2026-09-02 7:59 [PATCH v3] mm: memblock: show all region flags in debugfs Meijing Zhao
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